The connections of the vestibular nuclei will be studied in the cat using both anterograde and retrograde techniques. The anterograde techniques will utilize the Nauta silver method to demonstrate axonal degeneration following small non-electrolytic made under direct visual control in the cerebellum and brain stem. Projections to be studied intensively with this method will be: cerebello-vestibular connections, connections of associated small vestibular nuclei (Group Y), descending projections of the vestibular nuclei. The retrograde technique will be of two types: a) demonstration of increased acid phosphatase in neurons following distant transection of their axons b) localization of protein tracers (such as horseradish peroxidase) to demonstrate retrograde protein transport following injection of the tracer to the ending or endplate of efferent neurons. These methods will be employed to study: a) origin of ascending and descending efferent projections of the major vestibular nuclei, and b) organization of the oculomotor nuclear complex in the kitten.